Who will fill Richie McCaw's shoes?

As All Black captain Richie McCaw saunters away for some surgery, gliding and downtime after the World Cup glories, the selectors will ponder how best to safeguard his future.

He's heading towards his 31st birthday and while he remains near the apex of global stars in his openside flanker role, McCaw's best years are not in front of him.

His rugby smarts and indomitable spirit suggest McCaw can stay at his current prime level of performance for a few seasons yet. Surgery on his right foot should sort out the pain which inhibited his training during the World Cup and would have lowered a lesser athlete.

But seeing young Crusaders' flanker Matt Todd at training during the World Cup raised the interest on a variety of fronts.

First and foremost, despite the best denials the All Blacks could provide, there were alarms about McCaw's ability to get to the end of the tournament.

He managed, but only just, as his mental and physical expressions testified.

McCaw updated Peter Jones' 1956 description of fatigue after the series win against the Boks, with his "I'm absolutely shagged" revelation after the All Blacks 8-7 World Cup triumph.

Television footage of him in the dressing room showed the toll the game and tournament had taken on the All Black captain. He was exhausted. The warrior needed a rest.

Four months away from footy will do physical and mental wonders for him, and every other player and staff member of the World Cup group who battled to rugby's ultimate prize last Sunday. It'll give them all time to consider their futures.

"For a guy to play on one foot, not train for a month and play like [McCaw] did, was colossal," forwards coach Steve Hansen said.

It's a decade since McCaw succ-eeded Taine Randell as the team's No 7, when John Mitchell replaced Wayne Smith as coach and took the side to Ireland, Scotland and Argentina.

Marty Holah was the senior flanker but Mitchell preferred McCaw and his 103 test career began.

When McCaw's body has refused to cooperate, Holah, Daniel Braid, George Whitelock, Tanerau Latimer, Liam Messam, Adam Thomson and Victor Vito have deputised in tests while Scott Waldrom played in a tour game against Munster.

McCaw's contract with the NZRU runs through to the next World Cup. That might be another 50 tests for a new and revised coaching staff to minister and rebuild the side towards the tournament in England.

It would surprise if McCaw survived for that event, or wanted to. Only one captain in the history of the World Cups has attempted to defend a title and John Smit and the Boks fell at the quarter-finals this year.

McCaw may play on for a few years and has been an exceptional talent among a group of very good players. The All Blacks have been blessed to have both him and Daniel Carter in the same era.

"You can't go to the chemists and get the captain over the counter. He's the best leader this country's ever had," Graham Henry said.

The loose forward still has an enormous amount to give to an All Black side which will go through many changes before 2015. Selfless is a byword for his playing style and the next few years should be the perfect time for him to mentor a deputy.

Otherwise the All Blacks might be left with the choice England had not so long ago, of playing Neil Back who was nudging superannuation, or some untrained youth.

The opposing argument would come from Wales who kept pushing Martyn Williams out on to the paddock until he could hardly compete, before they uncorked Sam Warburton and then slapped the captaincy cloak around him as well.

The All Black selectors have been reluctant to operate with a specialist openside on the bench, preferring to go with the multidimensional skills of players like Thomson or Messam in case of damage. Next year they should reconsider.

They should pick a specialist reserve openside flanker in tests so McCaw can mentor him during the week and perhaps job-share during the internationals - invaluable tuition for young men like Todd, Luke Braid, Jack Lam or Sam Cane who are pushing to rise to international level as specialist No 7s.